The U.S. Supreme Court has refused to overturn legal immunity for telecom carriers that allegedly participated with a U.S. National Security Agency surveillance program during the last decade.

The Supreme Court, without comment, declined Tuesday to review a December 2011 appeals court decision upholding legal immunity for AT&T in its effort to assist the NSA to monitor telephone calls and Internet communications following the Sept. 11, 2001, terrorist attacks on the U.S.

The Electronic Frontier Foundation filed the class-action lawsuit, Hepting v. AT&T, in 2006. Congress in 2008 gave telecom carriers legal immunity for participating in the NSA program, and the EFF appealed a June 2009 dismissal of the case to the Ninth Circuit Court of Appeals, but the appeals court let the immunity stand.

The EFF and other civil liberties groups accused AT&T of participating in an illegal surveillance program run by the NSA. Officials with former President George W. Bush’s administration defended the program, saying it was necessary to fight terrorism.

“Evidence in the case includes undisputed evidence provided by former AT&T telecommunications technician Mark Klein showing AT&T has routed copies of Internet traffic to a secret room in San Francisco controlled by the NSA,” the EFF said on an information page about the case.

An AT&T spokesman wasn’t immediately available for comment.

EFF said it was disappointed in the Supreme Court’s decision. The decision “lets the telecommunications companies off the hook for betraying their customers’ trust and handing their communications and communications records to the NSA without a warrant,” Cindy Cohn, EFF’s legal director, said in an email.

The EFF has another case, Jewel v. NSA, moving forward, Cohn noted. “The government still claims that this massive program of surveillance of Americans is a state secret, but after 11 years and multiple congressional reports, public admissions and media coverage, the only place that this program hasn’t been seriously considered is in the courts—to determine whether it’s legal or constitutional,” she said. “We look forward to rectifying that.”

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